1. Field of the Invention
The present invention relates to a process for preparing a piperazinesulfonamide derivative and a pharmaceutically acceptable salt thereof. More specifically, the present invention relates to a process for preparing a piperazinesulfonamide derivative and a pharmaceutically acceptable salt thereof which have excellent antiallergic activity and thereby are useful as a medicament for preventing and treating diseases such as bronchial asthma, allergic rhinitis, atopic dermatitis, urticaria and the like.
2. Discussion of the Related Art
Conventionally, as processes for preparing a piperazinesulfonamide derivative, there have been known, for instance, process A, process B and process C which are described in WO95/19345 Pamphlet.
However, since the reaction processes of process A and process C are long, and the yield of the piperazinesulfonamide derivative is low, it cannot be said that these processes are industrially advantageous. In addition, since process B requires a long period of time for completion of the reaction, and the yield is not a satisfactory level, it cannot be said that process B is industrially advantageous.
Therefore, recently, it has been required to develop a process capable of industrially advantageously preparing a piperazinesulfonamide derivative in a short period of time and at high yield.
In view of the above prior art, the present invention has been accomplished, and an object of the present invention is to provide a process for efficiently and industrially advantageously preparing a piperazinesulfonamide derivative and a pharmaceutically acceptable salt thereof.
These and other objects of the present invention will be apparent from the following description.